Temporary electrical connectors for effecting a secure mechanical and electrical interconnection between a base unit and a portable electrical unit or appliance for providing electrical signals therebetween are well known. Electrical connectors for directly powering portable appliances or for recharging of batteries contained in the appliance employ a wide variety of connector systems in the prior art. For example, the appliance may be fitted with a socket or pin array for connection with a matching pin or socket array mounted in a cradle on the surface of or on a cable extending from a line powered, AC/DC voltage converter and charger base unit. In some systems, rechargeable batteries or battery packs may be pressed into mating receptacles of the portable unit during use and the base unit during recharging so that electrical contact is made by the battery terminals with spring contacts in the receptacles.
As long as the size of the appliance allows, receptacles and/or connectors of any size may be employed. In the simplest systems, the weight and shape of the portable appliance may be relied on to make secure electrical contact between simple surface contacts when the shaped appliance coupling surface is mated to the base unit coupling surface.
However, battery powered portable appliances, e.g. still photographic cameras, calculators, computers, telephones, dictation and music tape or solid state recorders, hand tools, etc., have progressively become smaller and lighter with advances in solid state electronic control units, rechargeable batteries and hardware. A problem exists in providing a simple, miniaturized electrical connection system that is secure to provide the recharging current for the batteries within the appliance or to make other electrical connections.
Simple magnetic aided, electrical connectors for an electrical cable are known wherein a permanent magnet is employed in one coupling half to attract a plate of ferrous, permeable material in the other half to maintain contact between mating electrical connector elements in each coupling half as shown in U.S. Pat. No. 3,786,391. The magnetic attraction and force of attachment depends on the size and strength of the permanent magnet, and it is difficult to achieve high attachment force in a small space.